The morbidities which are associated with obesity are more related to the distribution of adipose tissue in centrla versus peripheral depots than with the absolute amount of body fat. This study examines subcutaneous adipose tissue from abdominal, gluteal and femoral depots in vivo and in vitro in order to determine regional and gender related difference in adipose tissue morphology and biochemistry. In vivo studies are sonography of different depots and measurement of regional adipose tissue blood flow (by ethanol washout) and responsiveness to alpha- (antilipolytic) and beta- (lipolytic) adrenergic agonists using microdialysis probes in subjects at rest. In vitro studies are pathologic examination of full thickness wedge biopsies and subcutaneous adipose tissue biopsies from different anatomic regions. We have found a sexual dimorphism in the connective tissue structure of the dermis and subcutaneous adipose tissue depot of the thigh. Females demonstrate thin vertical septae and large lobules of adipocytes extending into the reticular dermis while subcutaneous tissue contained adipose tissue lobules of smaller size and the fibrous septa appeared thicker and were arranged in planes oblique, rather than perpendicular, to the epidermal surface. These connective tissue differences did not correlate with regional differences or inter-individual differences in adipose tissue metabolism or morphology.